Combustion apparatus for a boiler



Jan. 31, 1967 J D KIMMEL 3,301,305

- COMBUSTION APPARATUS FOR A BOILER Filed Nov. 5, 1965 4 Sheets-Sheet l INVEN'IOR. J D K IMMEL [W AT'I'ORNIZY Jan. 31, 1967 J D KIMMEL 3,301,305

COMBUSTION APPARATUS FOR A BOILER Filed Nov. 5, 1965 4 Sheets-Sheet 2 Jan. 31-, 1967 J D KIMMEL 3,301,305

COMBUSTION APPARATUS FOR A BOILER Filed NOV. 5, 1965 4 Sheets-Sheet 3 .Wllllllllllll' FIG?) Jan. 31, 1967 J D KIMMEL COMBUSTION APPARATUS FOR A BOILER 4 Sheets-Sheet 4 Filed 1965 #YITORNEY United States Patent 3,301,305 COMBUSTION APPARATUS FOR A BOILER J D Kimmel, Houston, Tex., assignor to Vapor Corporation, Chicago, 111., a corporation of Delaware Filed Nov. 5, 1965, Ser. No. 506,504 10 Claims. (Cl. 158-1.5)

This invention relate-s in general to a boiler or steam generator, and more particularly to a combustion apparatus for a boiler or steam generator, and still more particularly to a burner assembly for a combustion apparatus, and still more particularly to a burner assembly capable of providing proper combustion for heavy fuel oils, although other uses and purposes of the invention may be apparent to one skilled in the art.

The burner assembly of the present invention is adapted to be mounted on the head of a firepot and in alignment with a combustion throat in the head, and includes a holder for a single fuel nozzle to align the nozzle coaxially with the combustion throat, first and second means for mixing combustion air with a fuel spray atomized from the fuel nozzle, and means to provide an additional inlet for combustion air to prevent carbon build up. The means for mixing combustion air with a fuel spray includes spinning cones for vigorously spinning the combustion air to help mix the air with the fuel and to also increase the length of combustion products travel before leaving the firepot. Further, the means for injecting the combustion air is arranged to cause the combustion gases to recirculate in the firepot to enhance fuel vaporization and combustion. Thus, the burner assembly enables the burning of heavy fuel oils with small combustion volume. When referring to a boiler herein, it should be understood that such is also meant to include steam generators.

It is therefore an object of the present invention to provide a combustion apparatus for a boiler capable of burning heavy fuel oils with a small combustion volume.

Another object of this invention is in the provision of a combustion apparatus for a boiler that includes a burner assembly suitable for compact boilers and capable ofelfecting such complete combustion that the combustion products have low smoke readings.

A further object of the present invention is to provide a combustion apparatus for a boiler including a burner assembly that is structurally simple and inexpensive and capable of'providing a proper combustion with heavy fuel oils.

A still further object of this invention is in the provision of a combustion apparatus for a boiler including a burner assembly capable of providing proper atomization and vaporization of the fuel, and maximum travel of combustion gases before leaving the firepot.

Other objects, features and advantages of the invention will be apparent from the following detailed disclosure, taken in conjunction with the accompanying sheets of drawings, wherein like reference numerals refer to like parts, in which:

FIG. 1 is an end elevational view of a combustion apparatus according to the present invention;

FIG. 2 is a sectional view taken substantially along line 22 of FIG. 1;

FIG. 3 is an enlarged sectional view of the burner assembly according to the invention and showing its relationship with the firepot;

FIG. 4 is an elevational view of the burner assembly in FIG. 3 looking at it while facing the firepot;

FIG. 5 is an enlarged side elevational view, partly broken away and showing some parts in section of the main spinning cone employed in the burner assembly according to the invention;

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FIG. 6 is a fragmentary view of the spinning cone in FIG. 5 and looking in the direction of the arrows 6-6 of FIG. 5;

FIG. 7 is a diametrical sectional view taken through the secondary spinning cone of the burner according to the present invention; and

FIG. 8 is a fragmentary view of the spinning cone of FIG. 7 and looking in the direction of the arrows 8-8 of FIG. 7.

Referring now to the drawings and particularly to FIGS. 1 and 2, the combustion apparatus according to the present invention is generally indicated by the numeral 10, which includes generally a firepot 11 and a burner assembly 12 arranged within a plenum housing 13. The combustion apparatus 10 includes an attachment flange 14 for attaching same to a coil housing of a boiler or steam generator.

The plenum housing 13 includes an air inlet 15 adapted to be connected to a positive source of pressure such as that generated by a blower, and defines with the firepot 11 a plenum chamber 16 through which air is conveyed to the burner assembly 12. The plenum housing 13 includes a somewhat cylindrical section 17 surrounding the firepot 11 enclosed at the discharge end of the firepot by an annular end wall 18, and at the burner end of the firepot by an end wall 19.

The firepot 11 includes a refractory lined cylindrical shell 20 with a dome-shaped head 21 at one end and a choke 22 at the other end, and defining threin a combustion chamber 23. The burner assembly 12 is mounted on the firepot head 21 and aligned with a combustion throat 24 extending therethrough, whereby combustion gases are generated by the burner assembly 12 within the combustion chamber 24 and delivered through the choke 22 to a coil housing.

As seen particularly in FIGS. 3 and 4, the burner assembly 12 includes generally an annular mounting ring 25, having extending therefrom a plurality of mounting tubes 26, that receive a main spinning cone 27, a secondary spinning cone 28 separated therefrom by a spacer ring 29, a refractory cone 30, a sight glass mounting tube 31, a fuel nozzle mounting tube 32, and a pilot burner and scanner mounting tube 33.

A plurality of short rods 34 are suitably secured to the firepot head 21 and extend therefrom to be received in openings 35 formed in the mounting ring 25 which also includes set screws 36 for securing the ring to the rods. The mounting ring 25 is arranged in slightly spaced relation to the firepot head to define therebetween an air gap 37 that is preferably of a distance to provide the proper air distribution around the inside of the firepot head. As already indicated, the mounting tubes 26 extend from the ring 25 and are suitably secured thereto such as by welding or the like. The inner peripheral edge of the ring 25 is sized to be substantially coincident with the combustion throat 24.

The main spinning cone 27 and the secondary spinning cone 28 are essentially frusto-conical in shape although they are customarily called spinning cones in the combination of a burner. The main spinning cone 27 includes an upper or inner cone 38 and a lower or outer cone 39 spaced apart by a plurality of spinning vanes 40, and defining therebetween an air inlet passage 41. The spinning vanes 40 are suitably secured to the upper and lower cones such as by welding or the like to provide a single unit 27 defining the main spinning cone. As seen particularly in FIG. 5, the upper and lower cones 38 and39 are at a 45 angle with the horizontal as indicated by the arrow 42, and it should be appreciated that this angle may vary slightly and still obtain the desired result. While it is preferred that the angle be at 45,

it has been found that this angle is such that a short as possible fire be produced without causing coking and carbon build up upon the nozzle. The vanes 40 are arranged between the upper and lower cones so that they form about a angle with a tangent on the inner cone 38, as indicated by the arrow 43 in FIG. 6. Thus it can readily be seen that the air passing through the spinning cone 27 will be given a spinning movement as it is discharged into the firepot. Aligned sets of holes 44 and '45 are provided in the upper and lower cones, respectively, for mounting the spinning cone on the mounting tubes 26.

The secondary spinning cone 28, similarly includes upper or inner and lower or outer cones 46 and 47, respectively, separated by a plurality of spinning vanes 48, the cones being held together by being secured to the vanes and thereby coacting therewith to define a single unit. The cones 46 and 47 are inclined about 15 from the horizontal as indicated by the arrow 49, and the spinning vanes 48 are inclined about 15 from a tangent formed along the inner periphery of the lower cone 47 as indicated by the arrow 50. A plurality of sets of aligned mounting holes 51 and 52 are provided in the upper and lower cones 46 and 47, respectively so that the spinning cone 28 can be received on the mounting tubes 26. Thus, the cones 46 and 47 define an air inlet passage 53.

As seen in FIG. 3, the main spinning cone 27 is sized to inject a greater amount of air than the secondary cone 28- and at a different angle. Further, the discharge end of the air inlet passages 41 is radially inward from the discharge end of the air passage inlet 53. The spacer ring 29 separates the main spinning cone from the secondary spinning cone as seen in FIG. 3, and may be suitably secured to these cones such as by welding, if desired. The outer open end of the main spinning cone 27 is closed by the refractory cone 30 lined with refractory 54, and through which extend the mounting tubes 31, 32 and 33.

The mounting tube 31 coacts with a sight glassunit 55 as seen in FIGS. 1, 2 and 3, which extends outward of and is accessible outside of the end Wall 19 of the plenum housing 13. Similarly, a pilot burner and scanner unit 56 extends outward of the end wall 19 and is associated with the mounting tube 33. The fuel nozzle mounting tube 32 extends outward and through the end wall 19 to receive therein a single fuel nozzle 57 that is positioned so that its fuel discharge end terminates approximately coincident with the discharge end of the spinning cones 27 and 28. Further air openings 58 are provided in the fuel nozzle mounting tube 32 within the plenum chamber to allow air to enter the mounting tube behind the terminal end of the fuel nozzle. The method of construction of the burner assembly is such that all metal parts are air-cooled and allows most metal parts to be of mild steel. The only parts not constructed of mild steel include the spinning vanes 40 in the spinning cone Z7 and the spacer ring 29, these being preferably made of 16 gauge Inconel. Inasmuch as the fuel nozzle holder 32extends through the plenum chamber, it allows the fuel nozzle 57 to be set and not changed when the combustion chamber expands due to heating.

In operation, pressurized air is delivered to the plenum chamber to feed the spinning cones and the air gap 37, while pressurized fuel is delivered from the fuel nozzle 57 to be atomized within the firepot. The combustion is directed by the main spinning cone 27 to blast the nozzle fuel spray and impact a vigorous spin thereto to help mix the fuel and air. The smaller spinning cone 28 is used to increase the spinning action and also to catch any fuel spray that might get through the first blast of air delivered by the spinning cone 27. The spinning action also increases the length of fuel or combustion products travel before leaving the firepot to assure more complete combustion. Thus, all of the combustion air is mixed with the fuel spray atomized from the nozzle 57. The air delivered through the gap 37 will be spun but not as vigorously as the air delivered through the spinning cones and will be thrown out against the firepot top to prevent fuel rich spots for carbon to build. This air also provides an air flow across the top of the firepot head which protects against overheating. As seen in FIG. 3, a vortex 59 is created by the spinning air and defines a low pressure zone that causes the combustion gases to recirculate, as shown by the hollow arrows, which provides fast vaporization that helps the combustion. The solid arrows show air flow movement.

It will be understood that modifications and variations may be effected without departing from the scope of the novel concepts of the present invention, but it is understood that this application is to be limited only by the scope of the appended claims.

The invention is hereby claimed as follows:

1. A burner assembly adapted to be mounted on a firepot and in alignment with .a combustion throat thereof, said burner assembly comprising a tubular holder for a fuel nozzleaxially aligned with said combustion throat, a main spinning cone extending at a substantially 45 angle to a plane intersecting at right angles the axis of said holder and throat for directing a spinning blast of air toward the fuel spray discharged from anozzle received in said holder, a secondary spinning cone extending at a substantially 15 angle to a plane intersecting at right angles the axis of said holder and throat for directing a second spinning :blastof air toward the fuel spray and being spaced closer to said firepot than said main spinning cone, the main spinning cone being larger than said secondary spinning cone to thereby discharge a larger blast of air, and means for spacing the cones a slight distance from the firepot to define therebetween a small air gap.

2. The combination as defined in claim 1, wherein each .of said spinning cones includes inner and outer frustoconical sections interconnected by a plurality of spinning 3. The combination as defined 'in claim 2, wherein each spinning vane of said main spinning cone extends at a substantially 15 angleto a tangent along the innermost periphery of the inner frusto-conical section thereof.

.4. The combination as defined in claim 2, wherein each spinning vane of said secondary spinning cone extends at a substantially. 15 angle to a tangent along the innermost periphery of the inner frusto-com'cal section thereof.

5. The combination as defined in claim 2, wherein each spinning vane of each spinning cone. extends at a substantially 15 angle to a tangent along the innermost periphery of the inner frusto-conical section thereof.

6. The combination as defined in claim 1, wherein an annular spacer ring is positioned between said spinning 7. In a boiler, a combustion apparatus including .a firepot having a burner assembly mounted thereon and arranged within a plenum housing to define a plenum chamber therewith, the firepot including a cylindrical shell having a dome-shaped head atone end with a combustion throat extending centrally therethrough and a choke at the otherend thereof coacting with the shell and head to define a combustion chamber, the burner assembly being mounted on the firepot head in alignment with said combustion throat, said burner assembly comprising, a tubular fuel nozzle holder extending axially with said combustion throat and receiving a fuel nozzle therein, the nozzle end of which terminates in slightly spaced relation to said combustion throat, a main spinning cone extending at a substantially 45 angle to a plane intersecting at right angles the axis of said holder and throat for directing a spinning blast of air toward the fuel spray discharged from a nozzle received in said holder, a secondary spinning cone extending at a substantially 15 angle to a plane intersecting at right angles the axis of said holder and throat for directing a second spinning blast of air toward the fuel spray, said secondary spinning cone being coaxial with said main spinning cone and the combustion throat and being closer to the firepot than said main spinning cone, a spacer ring between said spinning cones, means spacing said secondary cone from said firepot to define a small air gap therewith, and a refractory cone on said main spinning cone with refractory on the side facing the combustion throat and through which extends said tubular fuel nozzle holder.

8. The combination as defined in claim 7, and a pilot and scanner tubular member extending through said refractory cone and refractory.

9. The combination as defined in claim 7, and a sight glass tubular member extending through said refractory cone and refractory.

10. The combination as defined in claim 7, wherein each of said spinning cones includes inner and outer frusto-conical sections interconnected by a pluhality oi spinning vanes, and each spinning vane of each cone extending at a substantially 15 angle to a tangent along the innermost periphery of the inner frusto-conical section thereof.

References Cited by the Examiner UNITED STATES PATENTS FREDERICK L. MATTESON, JR., Primary Examiner.

E. G. FAVORS, Assistant Examiner. 

1. A BURNER ASSEMBLY ADAPTED TO BE MOUNTED ON A FIREPOT AND IN ALIGNMENT WITH A COMBUSTION THROAT THEREOF, SAID BURNER ASSEMBLY COMPRISING A TUBULAR HOLDER FOR A FUEL NOZZLE AXIALLY ALIGNED WITH SAID COMBUSTION THROAT, A MAIN SPINNING CONE EXTENDING AT A SUBSTANTIALLY 45* ANGLE TO A PLANE INTERSECTING AT RIGHT ANGLES THE AXIS OF SAID HOLDER AND THROAT FOR DIRECTING A SPINNING BLAST OF AIR TOWARD THE FUEL SPRAY DISCHARGED FROM A NOZZLE RECEIVED IN SAID HOLDER, A SECONDARY SPINNING CONE EXTENDING AT A SUBSTANTIALLY 15* ANGLE TO A PLANE INTERSECT- 